Loud-speaking telephone system.



J; J. COMER.

LOUD SPEAKING TELEPHONE SYSTEM. APPLICATION FILED JULY 21; 191%.

LQM, 1 Patented my 24, 191?.

burn saurrns a rnwr eaten JOHN J. COMER, OF CHICAGO, ILLINCIS, ASSIGNOR TO AUTOMATIC ENUNCIATOR COM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

LOUD-SPEAKING TELEPHONE SYSTEM.

Speciiication of Letters Patent. i Patent-ad July 24L, IQ}? Application filed July 21, 1913. Serial No. 780,118.

To all whom it may concern:

Be it known that I, JOHN J. Corina, a :itizen of the United States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Loud-Speaking Telephone Sys-.

toms, of which the following is a specification.

IvIy invention relates to improvements in telephone systems, and more particularly to enunciating or music transmitting systems.

The object of my invention is to provide a system in which a highly increased efficiency of transmission is obtained, and one in which a plurality of transmitters can energize a maximum number of loud speaking receivers. V

A further object is to provide means whereby the receivers can be energized either from voice transmitters or from transmitters energized from a sound record.

These and other objects of my invention will be more readily understood by having reference to the accompanying drawings, in

which I have shown in diagrammatic form one embodiment of my invention.

I have there shown a battery B, to which are connected the line conductors 23, across which are a plurality of bridges each containing a microphone transmitter K and a fixed resistance 4 illustrated in the form of an incandescent lamp. In each of these bridges, it will be noticed that the points 56 at which the bridges connect with the line conductors 2-3 being permanently eonnected to opposite poles of the battery B,

. remain at substantially a constant potential. Vl hen one of the transmitters K is operated, its resistance varies. When the resistance is increased, the drop of potential between the points 5 and 7 is increased, and when the resistance of the transmitter is decreased the potential at 7 is correspondingly changed. We thus have in each bridge the till a as two points, 5 and 6, of constant potential,

and the point 7, between the fixed resistance 4 and the transmitter K, of a varying potential, the variation in this potential being proportionate to the variations and resistto ances of theatransmitter K. T

From this it will be seen that the vari; ation of potential betweenthe points 6 and 7 is similar to and proportionate to the variation between theepoints 5 ahd 6that is,

555 when the'transmitter K is operated, if a re- .it is, of course,

ceiver were connected across the points 6 and 7, it would be operated. in the same manner as if a receiver were connected across the transmitter itself at the points 5 and 7. To make use of this feature, I provide a plurality of transmitting circuits M, one around each of the transmitters K and likewise around each of the fixed resistances 4. In this manner I provide twice as many receiving circuits as there are microphone transmitters K, and each one of these re-' ceiving circuits is adapted to energize a plurality of repeaters or amplifiers R, which repeaters in turn energize a plurality of loud speaking receivers Z.

These amplifiers can be of any desired type, and I have illustrated same as comprising a mag'net 8,'a differential mierophone transmitter-.9, the armature of the magnet being connected to the movable electrode in the transmitter through the system not thoughtnecessary to describe same more i '1n detail.

At Y, I have indicated diagrammatically an apparatus for receiving vibrations from a record, and when it is desired to energize certain of the loud speaking receivers Z from this source, instead of from one of the microphones K, I have provided a pair of switches X-Y whereby by closing the switch Y K is cut 0% fromthe reproducing circuit. and the transmitter Y connected thereto. In a similar manner, when the switch Y is open and the switch X closed, the reproducing circuit is energized from the transmitters K. q i

It will thus be'seen that I have devised a very eflicient form of telephone system in which the fixed resistanceconneeted in series with the transmitters K are just as eflective in varying the potential in their respective receiving circuit M, as are the transmitters themselves. In this manner I am able to energizetwice as many receiving circuits as there are microphone transmitters.

,While I have illustrated and described one embodiment of my invention in connection with an apparatus of a particular type,

understood that I do not wish and opening X, the transmitter to limit myself to the exact construction v across said line circuit, each of said bridges 1 including a variable resistance transmitter and a fixed resistance connected in series, a receiving circuit connected directly around each of said transmitters, and a second receiving circuit connected directly around each of said fixed resistances.

3. In a telephone system, a battery, a variable resistance transmitter and a fixed resistance connected in series, a receiving circuit connected around said fixed resistance and excluding said transmitter, one or more amplifiers bridged across said receiving circuit, and one or more loud speaking receivers operatively connected with each of said amplifiers.

a. In a telephone system, a battery, a variable resistance transmitter and a fixed resistance connected in series, a receiving circuit connected directly around said transmitter,

of line conductors connected to opposite?- v poles of the battery, a plurality of bridges across said line circuit, each of said bridges including a variable resistance transmitter and a fixed resistance connected in series, a receiving circuit connected directly ;arou1i ;l each of said transmitters, a second receiving circuit connected directly around each of said fixed resistances, one or more amplifiers bridged across each of said receiving circuits, and one or more loud speaking receivers operatively connected with each of said amplifiers.

6. In a telephone system, a microphone transmitter adapted to be energized directly by voice currents, a second t-ransmitting apparatus adapted to be operated by vibrations received from a record, a receiving circuit,

loud speaking receivers operatively connected to said receiving circuit, and means for connecting-either one of said transmitters to said receiving circuit.

Signed by me at Chicago, Illinois, this 18th day of July, 1913.

' JOHN J. COMER- Witnesses:

LEON ZGLEMOLA, ALBERT ANDERSEN. 

